Circuit maker and breaker



Mamh 1934- E. o. OBERDICK ET AL 1,950,151

CIRCUIT MAKER AND BREAKER Filed Aug. 11, 1933 5 @AMM' i m v ATTORNEYS Patented Mar. 5, 1934- UNITE STATES PATENT OFFICE CHRCUIT MAKER AND BREAKER Application August 13, 1933, Serial No. 684,705

l Claims.

This invention relates to improvements in circuit breakers, it here particularly relating to improvements in the construction of the breaker arm of the breaker points such as are used in the ignition systems of automobiles.

One of the objects of the invention is to provide improved means for securing the contact point to the breaker arm.

Another object is to provide a breaker arm of reduced manufacturing cost by designing the same so as to employ a rubbing block consisting of a short portion of a flat strip of insulating material having a rectan ular crosssection, whose cost is lower than that'of the ang1e-sec--- ion rubbing blocks heretofore employed.

Other objects and advantages will appear in the following description as illustrated by the views in the drawing.

In the accompanying drawing:

Fig. 1 is a plan view of a. circuit breaker of the automotive type having an improved breaker arm shown therewith.

Fig. 2 is a side elevation on an enlarged scale of the breaker arm and its permanently attached accessories.

Fig. 3 is a top plan view of the arm shown in Fig. 2.

Fig. 4 is a bottom plan view of the arm.

Fig. 5 is a transverse section on the line 5-5 of Fig. 2.

Figs. 6 and 7 are enlarged transverse sections on the lines 6--6 and '77 of Fig. 2 respectively.

Fig. 8 is an enlarged section on the substantially horizontal line 88 of Fig. 2.

Fig. 9 is a. partial side elevation of a breaker arm constructed according to a modification.

Fig. 10 is a partial top plan View of the modified arm.

Fig. 11 is a partial top plan View of the blank which is later formed into the modified arm.

Referring to the drawing, the breaker arm is indicated at 1, and from its contour it will be evident that the arm may be produced from a flat, narrow strip of metal with little waste. To provide an arm of light weight, the material is comparatively thin, side-wise bending of the arm being pre'ented by the formation of a rib 2 in the arm, extending substantially throughout the arm. In the present case, the rib is V -shaped as best shown in Figs. 6 and '7.

In place in .the circuit breaker, the arm is pivotally mounted on a stud 3 in the plane of rotation of the cam 4, by the high points of which rated from the fixed contact point 6 secured to the circuit breaker apparatus, the arm being pressed to close the contact points by the action of a flat spring 7. Since the arm carries current, it is insulated from the mechanism of the circuit breaker by the interpositioning of an insulating bushing 8 between the arm and the stud 3, as bushn being forced into a hubbed opening at the pivotal end of the arm. The hub is indicated 9 and is an integral part of the arm, and slightly tapering to better grip and retain the bushing when the bushing is forced into place.

The breaker arm is given a limited rocking motion by means of the rotary cam 4 from which the arm is also insulated. The arm makes contact with the cam through the medium of an insulating member known as a rubbing block represented at 10. In the present case, the rubbing block is formed of flat hard fibre, being pierced and out off from a strip of that material at the desired length, and as seen in Fig. 2, is notched as at 11 and is secured by rivets 12 to the upturned tabs 13 obtained by notching the vertical leg i l of a small, metallic, angle-section member 15 whereby the rubbing block and member 15 are enabled to straddle the arm 1. The angle-section member 15 is secured to the lower edge of the arm 1, the horizontal leg 16 of the member being welded to the arm. The return spring '7, previously mentioned, slitted for the greater portion of its length, straddles the arm 1 longitudinally, and is secured at its forked end directly to the horizontal leg 16 of the member 15.

The arm is further provided with the usual contact point as mentioned. The contact point is secured to the arm in the following manner: The breaker arm blank before forming is provided with an extended tab shown in broken lines at l in Fig. 2, which tab is later formed into an eye 17 illustrated in Figs. 3 and 8. The stem 18 of a soft-metal contact support disk 19, to which the hard-metal point 20 has been previously welded is inserted upwardly in the eye and when in place is permanently secured by welding.

A modification in the manner of attaching the 100 contact point to the arm is shown in Figs. 9, 10 and 11. In the modified form the point .5 is secured directly to the arm, preferably by a brazing operation. In blanking out this arm, a small tab 1 of nearly completely circular outline of 105 the same diameter as the point is formed at the free end of the arm 1 as shown in Fig. 11, there remaining the necessary portion 1 where the tab is joined to the arm proper. In a. subsequent operation, the arm is given a one-quarter 110 twist at the portion 1, the arm assuming the form seen in Figs. 9 and 10. The point is then brazed to the arm as follows: The arm is inverted, and on the upturned surface of the tab the contact point 5 is deposited with a thin disk 20 of spelter or other brazing material interposed between the point and tab, after which sufilcient heat is applied to bring the parts to the brazing heat. As the spelter melts, the point settles to the tab, and due to the surface tension of the melted spelter and also to the fact that the diameters of the tab and the point are equal, the point automatically centers itself on the tab. It will be seen from the foregoing description that I have devised an improved breaker arm adaptable to being produced from strip material of a width but little greater than the finished arm, of such light weight as to render inertia forces negligible even at high speed, constructed according to a design which permits the use of a rubbing block formed of flat strip insulating material having a rectangular cross-section whose expense is less than that of angle-section insulating material, whereby with other consideration such as the reduced waste material mentioned, the total cost of the finished arm is reduced.

Having thus described our invention, we claim: 1. In a circuit breaker of the character described, a substantially flat metallic arm, a contact point secured to one end of said arm, an airgle section member having one leg secured to an edge of said arm at an intermediate point in the length thereof with the other leg straddling said arm, and a cam rubbing block of insulating materlal also straddling said arm and secured to the last-mentioned leg of said angle section scribed, a flat metal arm, one end of said arm being bent to form an eye, a contact point secured in said eye, a bushing in the other end of said arm to form a pivot bearing, and a rubbing block secured to an intermediate point of said arm.

3. In a circuit breaker of the character described, a substantially flat, longitudinally ribbed metallic arm, an insulating pivot bushing inserted at one end, a contact point stem receiving eye at the other end of said arm, a contact point secured in said eye, a metallic angle-section member having one leg secured to an edge of said arm at a point intermediate the ends thereof, the other leg being notched and straddling the arm, and an insulating notched rubbing block of flat material secured to the notched leg of the angle-section member and also straddling the arm.

4. In a circuit breaker of the character described, a substantially fiat, longitudinally ribbed metallic arm, an insulating pivot bushing inserted at one end, a contact point stem receiving eye at the other end formed of a tab integrally attached to the end of said arm, a contact point secured in said eye, a metallic angle section member having one leg secured to an edge of said arm at a. point intermediate the ends thereof, the other leg being notched and straddling the arm, and an insulating notched rubbing block secured to the notched leg of the angle-section member and also straddling the arm, and a return spring notched at one end to straddle the arm secured to the first-mentioned leg of the angle-section member.

ERVIN O. OBERDICK. CLARENCE RINGWALD. 

